split-gep-and-gvn.ll
10.5 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda -mcpu=sm_20 \
; RUN: | FileCheck %s --check-prefix=PTX
; RUN: opt < %s -mtriple=nvptx64-nvidia-cuda -S -separate-const-offset-from-gep \
; RUN: -reassociate-geps-verify-no-dead-code -gvn \
; RUN: | FileCheck %s --check-prefix=IR
; Verifies the SeparateConstOffsetFromGEP pass.
; The following code computes
; *output = array[x][y] + array[x][y+1] + array[x+1][y] + array[x+1][y+1]
;
; We expect SeparateConstOffsetFromGEP to transform it to
;
; float *base = &a[x][y];
; *output = base[0] + base[1] + base[32] + base[33];
;
; so the backend can emit PTX that uses fewer virtual registers.
@array = internal addrspace(3) constant [32 x [32 x float]] zeroinitializer, align 4
define void @sum_of_array(i32 %x, i32 %y, float* nocapture %output) {
.preheader:
%0 = sext i32 %y to i64
%1 = sext i32 %x to i64
%2 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %0
%3 = addrspacecast float addrspace(3)* %2 to float*
%4 = load float, float* %3, align 4
%5 = fadd float %4, 0.000000e+00
%6 = add i32 %y, 1
%7 = sext i32 %6 to i64
%8 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %7
%9 = addrspacecast float addrspace(3)* %8 to float*
%10 = load float, float* %9, align 4
%11 = fadd float %5, %10
%12 = add i32 %x, 1
%13 = sext i32 %12 to i64
%14 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %13, i64 %0
%15 = addrspacecast float addrspace(3)* %14 to float*
%16 = load float, float* %15, align 4
%17 = fadd float %11, %16
%18 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %13, i64 %7
%19 = addrspacecast float addrspace(3)* %18 to float*
%20 = load float, float* %19, align 4
%21 = fadd float %17, %20
store float %21, float* %output, align 4
ret void
}
; PTX-LABEL: sum_of_array(
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG:%(rd|r)[0-9]+]]{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+4{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+128{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+132{{\]}}
; IR-LABEL: @sum_of_array(
; TODO: GVN is unable to preserve the "inbounds" keyword on the first GEP. Need
; some infrastructure changes to enable such optimizations.
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33
; @sum_of_array2 is very similar to @sum_of_array. The only difference is in
; the order of "sext" and "add" when computing the array indices. @sum_of_array
; computes add before sext, e.g., array[sext(x + 1)][sext(y + 1)], while
; @sum_of_array2 computes sext before add,
; e.g., array[sext(x) + 1][sext(y) + 1]. SeparateConstOffsetFromGEP should be
; able to extract constant offsets from both forms.
define void @sum_of_array2(i32 %x, i32 %y, float* nocapture %output) {
.preheader:
%0 = sext i32 %y to i64
%1 = sext i32 %x to i64
%2 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %0
%3 = addrspacecast float addrspace(3)* %2 to float*
%4 = load float, float* %3, align 4
%5 = fadd float %4, 0.000000e+00
%6 = add i64 %0, 1
%7 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %6
%8 = addrspacecast float addrspace(3)* %7 to float*
%9 = load float, float* %8, align 4
%10 = fadd float %5, %9
%11 = add i64 %1, 1
%12 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %11, i64 %0
%13 = addrspacecast float addrspace(3)* %12 to float*
%14 = load float, float* %13, align 4
%15 = fadd float %10, %14
%16 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %11, i64 %6
%17 = addrspacecast float addrspace(3)* %16 to float*
%18 = load float, float* %17, align 4
%19 = fadd float %15, %18
store float %19, float* %output, align 4
ret void
}
; PTX-LABEL: sum_of_array2(
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG:%(rd|r)[0-9]+]]{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+4{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+128{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+132{{\]}}
; IR-LABEL: @sum_of_array2(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33
; This function loads
; array[zext(x)][zext(y)]
; array[zext(x)][zext(y +nuw 1)]
; array[zext(x +nuw 1)][zext(y)]
; array[zext(x +nuw 1)][zext(y +nuw 1)].
;
; This function is similar to @sum_of_array, but it
; 1) extends array indices using zext instead of sext;
; 2) annotates the addition with "nuw"; otherwise, zext(x + 1) => zext(x) + 1
; may be invalid.
define void @sum_of_array3(i32 %x, i32 %y, float* nocapture %output) {
.preheader:
%0 = zext i32 %y to i64
%1 = zext i32 %x to i64
%2 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %0
%3 = addrspacecast float addrspace(3)* %2 to float*
%4 = load float, float* %3, align 4
%5 = fadd float %4, 0.000000e+00
%6 = add nuw i32 %y, 1
%7 = zext i32 %6 to i64
%8 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %7
%9 = addrspacecast float addrspace(3)* %8 to float*
%10 = load float, float* %9, align 4
%11 = fadd float %5, %10
%12 = add nuw i32 %x, 1
%13 = zext i32 %12 to i64
%14 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %13, i64 %0
%15 = addrspacecast float addrspace(3)* %14 to float*
%16 = load float, float* %15, align 4
%17 = fadd float %11, %16
%18 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %13, i64 %7
%19 = addrspacecast float addrspace(3)* %18 to float*
%20 = load float, float* %19, align 4
%21 = fadd float %17, %20
store float %21, float* %output, align 4
ret void
}
; PTX-LABEL: sum_of_array3(
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG:%(rd|r)[0-9]+]]{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+4{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+128{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+132{{\]}}
; IR-LABEL: @sum_of_array3(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33
; This function loads
; array[zext(x)][zext(y)]
; array[zext(x)][zext(y)]
; array[zext(x) + 1][zext(y) + 1]
; array[zext(x) + 1][zext(y) + 1].
;
; We expect the generated code to reuse the computation of
; &array[zext(x)][zext(y)]. See the expected IR and PTX for details.
define void @sum_of_array4(i32 %x, i32 %y, float* nocapture %output) {
.preheader:
%0 = zext i32 %y to i64
%1 = zext i32 %x to i64
%2 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %0
%3 = addrspacecast float addrspace(3)* %2 to float*
%4 = load float, float* %3, align 4
%5 = fadd float %4, 0.000000e+00
%6 = add i64 %0, 1
%7 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %1, i64 %6
%8 = addrspacecast float addrspace(3)* %7 to float*
%9 = load float, float* %8, align 4
%10 = fadd float %5, %9
%11 = add i64 %1, 1
%12 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %11, i64 %0
%13 = addrspacecast float addrspace(3)* %12 to float*
%14 = load float, float* %13, align 4
%15 = fadd float %10, %14
%16 = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %11, i64 %6
%17 = addrspacecast float addrspace(3)* %16 to float*
%18 = load float, float* %17, align 4
%19 = fadd float %15, %18
store float %19, float* %output, align 4
ret void
}
; PTX-LABEL: sum_of_array4(
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG:%(rd|r)[0-9]+]]{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+4{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+128{{\]}}
; PTX-DAG: ld.shared.f32 {{%f[0-9]+}}, {{\[}}[[BASE_REG]]+132{{\]}}
; IR-LABEL: @sum_of_array4(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33
; The source code is:
; p0 = &input[sext(x + y)];
; p1 = &input[sext(x + (y + 5))];
;
; Without reuniting extensions, SeparateConstOffsetFromGEP would emit
; p0 = &input[sext(x + y)];
; t1 = &input[sext(x) + sext(y)];
; p1 = &t1[5];
;
; With reuniting extensions, it merges p0 and t1 and thus emits
; p0 = &input[sext(x + y)];
; p1 = &p0[5];
define void @reunion(i32 %x, i32 %y, float* %input) {
; IR-LABEL: @reunion(
; PTX-LABEL: reunion(
entry:
%xy = add nsw i32 %x, %y
%0 = sext i32 %xy to i64
%p0 = getelementptr inbounds float, float* %input, i64 %0
%v0 = load float, float* %p0, align 4
; PTX: ld.f32 %f{{[0-9]+}}, {{\[}}[[p0:%rd[0-9]+]]{{\]}}
call void @use(float %v0)
%y5 = add nsw i32 %y, 5
%xy5 = add nsw i32 %x, %y5
%1 = sext i32 %xy5 to i64
%p1 = getelementptr inbounds float, float* %input, i64 %1
; IR: getelementptr inbounds float, float* %p0, i64 5
%v1 = load float, float* %p1, align 4
; PTX: ld.f32 %f{{[0-9]+}}, {{\[}}[[p0]]+20{{\]}}
call void @use(float %v1)
ret void
}
declare void @use(float)